Nitrocellulose containing explosive compositions and methods of preparing same



June 1, 1965 VON HOLT 3,186,882

NITROCELLULOSE CONTAINING EXPLOSIVE COMPOSITIONS AND METHODS OF PREPARING SAME Filed Jan. 12, 1962 PETN N\TROGLYCER|N B 100% 9b "4, so A, 70% 6 N\TROCELLULUSE INVENTOR ATTORNEY NITROCELLULOSE CONTAlNlNG EXPLGSIVE COMPOSITIONS AND METHODS OF PRE- PARING SAME Erich von Holt, 1 Heisterbacherhof Strasse, Bonn, Germany Filed Jan. 12, 1962, Ser. No. 165,831 21 Claims. (Cl. 14918) The present invention relates to explosive compositions, in particular high explosives, which are in the solid state at the temperature at which they are to be used (solid state meaning the state of a compound or mixture which is neither liquid nor gaseous), and to the methods of preparing such explosive compositions.

My invention is concerned with explosive compositions having the state of a colloidal homogeneous substance containing at least 25% by weight of nitrocellulose.

It is known to obtain nitrocellulose containing explosives by gelatinizing such substances either by dry stirring in the hot state without using a solvent or by means of suitable solvents.

For such a preparation, it has been usual, up to the present time, simultaneously to use additional substances of two kinds, one acting as a stabilizer and the other as a plasticizer. Generally the stabilizers are substituted derivatives of urea such as centralite (diethyldiphenylurea, dimethyldiphenylurea or methylethyldiphenylurea) and the plasticizers are substituted urethanes (such as diphenylurethane, ethylphenylurethane) and dibutyl phthalate.

Making use of two kinds of substances is already a complication, but a further difficulty arises from the fact that the stabilizers usually employed, such as centralite, conflict with the action of the plasticizers. As a rule, these stabilizers tend to harden the explosive compositions and to make them brittle, which has an unfavourable influence upon the qualities and possibilities of utilisation of these explosive compositions.

It has however been proposed to use various additional substances acting both as stabilizers and as plasticizers, but these substances have not been satisfactory for practical purposes.

According to my invention, to make a material as above stated, that is to say a colloidal homogeneous explosive composition containing at least 25 by weight of nitrocellulose, I incorporate into the mass of the starting mixture, both as a stabilizer and as a plasticizer, from 3 to 8% by weight of at least one water-insoluble soap, of the group consisting of organic base-fatty acid salts and metal-fatty acid salts, the metal being one of the group consisting of calcium and magnesium, after which the mixture thus obtained is gelatinized.

The organic base above referred to is a compound having a linkable nitrogen atom and I may for instance use for this purpose aniline, toluidine, xylidine, naphthylamine, diphenylamine, urea, hydrazine, urethane, either in the simple or in the substituted state, and dicyandiamide, ethanolamines in the simple state.

Tests show, in a rather surprising manner, that each of the above indicated soaps acts both as a stabilizer and as a plasticizer, for nitrocellulose either alone or in combination with at least one explosive oil, themselves either alone or combined with crystalline brisant explosives. By explosive oil is meant in the present specification, a polynitrate of a polyhydric alcohol, such as glyceryl trinitrate (nitroglycerin), diethylene glycol dinitrate, triethylene glycol dinitrate, isobutylglyceryl trinitrate, propylene glycol dinitrate and ethylene glycol dinitrate.

Patented June 1, 1965 ice This property permits of notably simplifying the method of preparing the explosive composition and of reducing the amount of materials to be kept in store, which ensures a serious economy, both from the chemical and from the industrial point of view.

Furthermore, the previously mentioned conflict between the usual stabilizers and plasticizers is avoided by the instant invention.

Preferably, gelatinizing is effected by dry stirring in the hot state, at a temperature ranging from 60 C. to C., without using a solvent. The plasticizing action of the soaps is of course more effiicent in this case and it is thus possible to make the substance to be gelatinized as fluid as it may be desired.

The above referred to soaps and their mixtures have been subjected to experiments which have shown that some of them are preferable to the others.

Thus it is necessary to make use of a soap containing at least 50% by weight of products of reaction of a non-saturated fatty acid, such as oleate, erucate, bras sidate, linoleate, linolenate and ricinoleate, the remainder of the soap being products of reaction of saturated fatty acids such as stearate, palmitate and arachidate. Furthermore, the soap may be constituted by a mixture of metallic soaps and organic base soaps as above mentioned, the amount of the first mentioned soaps being at least equal by weight to that of the second mentioned soaps.

The method according to the present invention permits of preparing smokeless powders, either from a mixture chiefly constituted by nitrocellulose or from a mixture containing by Weight from 25% to 68% of nitrocellulose and from 15% to 42% of an explosive oil.

It also makes it possible to prepare brisant explosive compositions by starting from substances containing nitrocellulose, at least one explosive oil and crystal-. line brisant solid explosives. I

In this case, the soap or soaps introduced into the mixture not only have a stabilizing and plasticizing effect, but also exert a lubricating action which permits of incorporating into the mixture, without danger of explosion when it is prepared, a very high proportion of crystalline brisant explosives, which are normally very sensitive to friction and shocks. Among these crystalline explosives, I may mention some organic explosives such as trinitrotoluene (TNT), tetryl, pentaerythritol tetranitrate (PET N cyclotrimethylene trinitramine (cyclonite or hexogen), nitroguanidine, dinitrophenylglycol ether nitrate and trinitrophenyl ether nitrate. These crystalline explosives are used in a finely divided state, their particles preferably having a size ranging from 0.1 to 2 mm.

For the explosive compositions which contain a solid crystalline explosive, an explosive oil and water-insoluble soaps, percentage limits should be complied with as specified hereinafter with reference to the ternary diagram, which constitutes the only figure of the appended drawing.

It will be supposed that:

a is the percentage by weight of the explosive oil, for instance nitroglycerin;

b is the percentage by weight of nitrocellulose; and

c is the percentage by weight of the crystalline explosive,

These three percentages being calculated in relation to the total weight of these three components, so that a+b+c=l00.

It will be supposed also that d is the percentage by weight of the water-insoluble soap, also calculated in relation to the total weight of the three first mentioned components.

Then, according to by invention, these four values a, b, c, d must comply with the following relations:

Relations 1 and 2 mean that the permissible amounts for the explosive oil, the nitro cellulose and the crystalline explosive must be located, within, or on, the perimeter of quadrilateral ABCD, in the graphic representation of the ternary diagram where the three systems of coordinates relate to the three above mentioned percentages a, b and 0, respectively. As a matter of fact line AB corresponds to a=45, line 'BC to [1 :25, line CD to a=30 and line AD to b=2c+41.

The percentages of the three main explosive components such as defined by Relations 1, 2 and 3 (or graphically on the appended diagram by quadrilateral ABCD) are critical for the following reasons.

If the nitrocellulose percentage is chosen outside of quadrilateral ABCD and in the vicinity of point D thereof, the mixture ,to be gelatinized is very hard and therefore very dangerous to roll and the explosive composition that may be obtained despite this danger is difiicult to detonate by means of a primer. 7

If the percentage of explosive oil is chosen higher than 45, i.e. above'line AB, the initial mixture is very soft and some amount of explosive oil in excess may fail to be incorporated in the mixture, which makes rolling very dangerous. The explosive composition'that is obtained exudes explosive oil, which makes it unstable, despite the addition of water-insoluble soap.

If the percentage of crystalline explosive is higher than 45, that is to say beyond point C, this explosive may explode during the rolling operation because the particles of crystalline explosive are liable to rub against one another and against the rolling cylinders.

Concerning the water-insoluble soap, its stabilizing action becomes insufiicient when its percentage (d) becomes lower than 3 whereas it exaggeratedly reduces the explosive power of the composition when said percentage is higher than 8. It is also quite necessary to have the water-insoluble soap incorporated in the mass of the composition because if it merely coated the grains of the composition superficially, no appreciable stabilizing effect would be obtained. Finally, experience teaches that the water-soluble salts of fatty acids (either unsaturated or saturated) reduce the stability of the explosive composition instead of increasing it and that water-insoluble soaps have a much greater stabilizing influence if they are obtained from unsaturated fatty acids instead of saturated fatty acids.

In the method of preparing brisant explosive compositions, as above indicated, there may be added to the mixtur'e, before the gelatinizing step, at least one salt capable of giving off oxygen said salt being preferably an alkaline nitrate such as ammonium nitrate. I may also include thereinto, before the gelatinizing step, a mixture having a thermal effect, that is to say having a blasting and/ or an incendiary effect, such a mixture being for instance constituted by barium nitrate and powdered aluminum. In any event, the explosive composition according to my invention contains at least 90% by Weight of the explosive ingredients constituted by nitrocellulose, the explosive oil and the crystalline brisant explosive.

I will now give examples of the method according to the present invention.

Example 1 7 Preparation of a smokeless powder by 'gelatinization of nitrocellulose by means of a solvent:

(A) The nitrocellulose is kneaded, with the addition of a mixture of ether and alcohol in the ratio of two to one, to 10% by weight of soap insoluble in water, this soap consisting of 65% of magnesium oleate, 20% of aluminum stearate and 15 of calcium stearate until a homogeneous gelatin is obtained. This gelatin is then treated in a press in such manner as to form cylindrical elements of the desired diameter which are cut to the desired length. In order to eliminate the solvent, the usual washing and drying operations are performed.

(B) In accordance with the process above described under 1 (A), I prepare in the desiredstate a gelatin containing 4% of a water-insoluble soap consisting of 60% of magnesium oleate, 20% of calcium stearate and 20% of barium palmitate in combination with 4% of an oleate of urea and diphenylamine. 5

Example 2 Preparation of a smokeless powder by gelatinizing a mixture of nitrocellulose and an explosive oil (nitroglycerin) by means of solvent:

I knead and make homogeneous (while cooling with Water and adding acetone) a mixture, wetted to about 8%, of 40% of nitroglycerin and 60% of nitrocellulose with 5% (with respect to dry weight of the total composition) of a water-insoluble soap consisting of 85% of calcium oleate and 1.5% of magnesium stearate and with 2% (also with respect to the dry weight of the total composition) of the product resulting from the reaction of stearic acid with diethanolamine and aniline. The gelatin thus obtained is subsequently rolled by means of cooled cylinders into plates of the desired thickness. After drying at about 40%. in order to eliminate the solvent, the plates are cut into discs, rings, sheets or strips.

. Example 3 Preparation of a smokeless powder by gelatinization without solvent of a mixture of nitrocellulose and an explosive oilz.

(A) In a container filled with water, I introduce and uniformly distribute, by stirring, nitrocellulose, then cliethyleneglycol dinitrate and also the water-insoluble soaps and other reaction products as hereinafter indicated.

Thecomposition is as follows. 65% of nitrocellulose,

28% of diethylene glycol dinitrate and 7% of other components. These other components consists of 5% of a water-insoluble soap constituted by 70% of calcium oleate, 18% of magnesium oleate, 12% of calcium stearate and of 2% of the reaction products of oleic or stearic acid with alphanaphthylamine and urea. The combination above stated is then passed through a centrifugal machine so as to reduce the percentage of water to about 30%, then gelatinization is performed without making use of solvents by the combined action of pressure and heat in a rolling machine. The plates thus obtained which are made of a mass of colloidal powder analogous to horn are cut into strips or small blocks, or are treated in the hot state in a hydraulic press so as to obtain extrusions of the desired shape which are subsequently dried if necessary. (B) According to the process above indicated under 3 (A), I prepare a thermoplastic homogeneous colloid which, in addition to 39%, of nitroglycerin and 57% of nitrocellulose, contains 3% of a water-insoluble soap consisting of of calcium oleate, 10% of calcium palmitate and 10% of aluminum stearate.

Example 4 Preparation of brisant explosives compositions by without solvent, of a mixture of nitrocellulose, explosive oils and crystalline solid explosives: (A) I form under water a mixture of 40% of nitrocellulose, 36% of nitroglycerin, 17.5% of PETN, 3.5% of nitroguanidine and 3% of calcium oleate. These quantities of components correspond, with the above definition of the percentages, to a=37.1; 11:41.2; c=21.7 and d=3.1 (point 7 of the diagram).

After a first dehydration of the compositionin a centrifugal machine, the percentage of water in the mass is reduced to about 8-10%, by means of a worm press. Then the mass is gelatinized at 90 C. in a rolling machine and is finally given the shape of a body of the desired section by treatment, in the hot state, in a press.

(B) According to the process above indicated under 4 (A), I prepare compressed bodies by means of a mixture containing 45% of nitrocellulose, 3% of nitroglycerin or diethyleneglycol dinitrate, 9% of PETN, 10% of ammonium or potassium perchlorate and 3% of calcium oleate (i.e. :34; 22:46.4; c=19.6 and d=3.l as shown by point g of the diagram).

(C) According to the process above indicated under 4 (A), I prepare explosive compositions (designated in the following table by number 1 to 9 inclusive), the percentages (as above defined) of their components being given in columns a, b, c and d. The last column indicates the stability coetficients of these explosive compositions. These stability coefiicients are given by the Holland test which consists in determining the Weight loss (percent) of a sample of the explosive kept in a closed tube at 105 for 72 hours.

Percent- Stability ages a b c :1 seemeicnts 36. 42. 65 20.85 (PETN) 4.2 1. 650.66

guanidine).

In the explosive Compositions 1 to 6 inclusive, the Water-insoluble soap is calcium oleate. In Composition 7, this soap is magnesium oleate. In Composition 8 it consists of a mixture of 9 parts of calcium oleate with 1 part of calcium stearate. In Composition 9, this soap consists of a mixture of 6 parts of calcium oleate with 4 parts of calcium stearate.

In all these compositions, the explosive oil is nitroglycerin or diethylene glycol dinitrate or a mixture of both.

Example 5 Preparation of brisant explosive compositions by gelatinization without solvent of a mixture of nitrocellulose, explosive oil and crystalline solid explosives with the addition of a salt capable of giving off oxygen:

I prepare under water a homogeneous mixture containing 46.5% of nitrocellulose, 33.5% of nitroglycerin or diethylene glycol dinitrate, 16% of PETN or cyclonite, 4% of a water-insoluble soap consisting of 88% of calcium oleate, 10% of magnesium stearate and 2% of aluminium oleate, and I reduce the percentage of water in this mixture by centrifugation to less than 30%. I further reduce the percentage of water by passing the substance several times through a rolling machine until no water leaks out when the substance is compressed. At this time, I add to the still aqueous substance a salt capable of giving off oxygen, such as ammonium or sodium nitrate, in such manner that the introduction of this salt is finished during the rolling operation, before a complete gelatinizing efiect is achieved.

The percentage of the added salt it about from 5 to 10% of the final composition, after homogeneous mixing of all the components, at the end of gelatinization.

These quantities of components correspond with the above definition of the percentages, to 11:34.9; b=48.4; c=16.7; 11:4.2 (point h of the diagram).

In a general manner, while I have described several specific examples of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made therein without departing from the principle of my invention as comprehended within the scope of the appended claims.

This application is a continuation in part of my prior US. patent application Ser. No. 563,199 filed February 3, 1956, now abandoned.

What I claim is:

1. The method of preparing colloidal blocks of an explosive composition which comprises incorporating into the mass of an explosive substance containing 25 to 100% by weight of nitrocellulose, for stabilizingand plastifying purposes, from 3 to 8% by weight of an additive constituted by at least one water insoluble soap selected from the group consisting of water insoluble calcium, magnesium and amine salts of saturated and unsaturated fatty acids, said additive comprising at least 50% by weight of unsaturated fatty acid salt, and gelatinizing the mixture thus obtained.

2. The method according to claim 1 wherein said amine salt is an ethanolamine salt.

3. The method according to claim 1 wherein said amine salt is a diphenylamine salt.

4. The method according to claim 1 wherein said amine salt is a naphthylamine salt.

5. The method according to claim 1 in which gelatinizing is carried out by dry stirring in the hot state.

6. The method according to claim 1 in which said explosive substance includes from 25 to 68% by weight of nitrocellulose and from 15 to 42% by weight of a polynitrate of a polyhydric alcohol.

7. The method of preparing an explosive composition which comprises mixing together nitrocellulose, an explosive oil constituted by at least one alcohol nitrate of the group consisting of nitroglycerin and diethylene glycol dinitrate, a crystalline brisant explosive in a finely divided solid state constituted by at least one body of the group consisting of pentaerythritol tetranitrate, cyclonite, nitroguanidine, trinitrotoluene, dinitrophenylglycol ether nitrate and trinitrophenylglycol ether nitrate, and, for stabilizing and plastifying purposes, an additive constituted by at least one Water insoluble soap selected from the group consisting of water insoluble calcium, magnesium and amine salts of saturated and unsaturated fatty acids, the percentages by weight, designated by a, b and 0 respectively, of explosive oil, nitrocellulose and crystalline explosive with respect to the total weight of the latter three constituents being determined by the following conditions: 30 a 45 and 25 b 2c+41, and the ponderal proportion of said additive with respect to the whole of said three constituents ranging from 3 to 8%, and gelatinizing the mixture thus obtained.

8. The method according to claim 7 in which gelatinizing is carried out by stirring at a temperature ranging from 60 to 100 C.

9. The method according to claim 7 which further comprises adding to the mixture of nitrocellulose, explosive oil, crystalline brisant explosive and water-insoluble additive, before said mixture is gelatinized, an alkaline nitrate.

10. The method according to claim 7 wherein said additive comprises at least 50% by weight of unsaturated fatty acid salt.

11. A colloidal explosive composition consisting in explosive ingredients and in a stabilizing and plastifying substance, at least by weight of said explosive ingredients being constituted by nitrocellulose, an explosive oil and a crystalline brisant explosive in a finely divided solid state, said explosive oil being constituted by at least one polynitrate of a polyhydric alcohol and the crystalline brisant explosive being constituted by at least one body of the group consisting of pentaerythritol tetranitrate, cyclonite, nitroguanidine, trinitrotoluene, dinitrophenylglycol ether nitrate, the percentages by weight, designated by a, b and 0 respectively, of explosive oil, nitrocellulose and crystalline explosive with respect to the total Weight of the latter three constituents being determined by the following conditions: 30 a 45 and 25 b 2 +41, said 3,1ee,ss2 i said stabilizing and plastifying substance being constituted by at least one water-insoluble soap selected from the group consisting of water'insoluble calcium, magnesium salts of saturated and unsaturated fatty acids, the ponderal proportion of said stabilizing and plastifying substance with respect to the whole of said three constituents ranging from 3 to 8%.

Y 12. A colloidal explosive according to claim 11 wherein the stabilizing and plastifying substance contains from 50 to 100% by weight of calcium oleate.

13. A colloidal explosive according to claim 11 wherein the stabilizing and plastifying substance contains from 50 to 100% by weight of magnesium oleate.

14. A colloidal explosive according to claim 11 wherein the stabilizing and plastifying substance contains from S0 to 100% by weight of calcium erucate.

15. A colloidal explosive according to claim 11 wherein the stabilizing and plastifying substance contains from 50 to 100% by weight of magnesium erucate.

16. A colloidal explosive according to claim 11 wherein the stabilizing and plastifying substance contains from 50 to 100% by weight of calcium brassidatei -O 0 17. A colloidal explosive according to claim 11 wherein the stabilizing and plastifying substance contains from 50 to 100% by Weight of magnesium brassidate.

18. A colloidal explosive according to claim 11 wherein the stabilizing and plastifying substance contains from 50 to 100% by weightof calcium linoleate.

1-9. A colloidal explosive according to claim 11 Wherevin the stabilizing and plastifying substance contains from 50 to 100% by weight of magnesium linoleate.

20. A colloidal explosive according to claim 11 wherein the stabilizing and plastifying substance contains from 50 to 100% by weight of calcium ricinoleate.

21. A colloidal explosive according to claim 11 wherein .the stabilizing and plastifying substance contains from 

1. THE METHOD OF PREPARING COLLOIDAL BLOCKS OF AN EXPLOSIVE COMPOSITION WHICH COMPRISES INCORPORATING INTO THE MASS OF AN EXPLOSIVE SUBSTANCE CONTAINING 25 TO 100% BY WEIGHT OF NITROCELLULOSE, FOR STABLIZING AND PLASTIFYING PURPOSES, FROM 3 TO 8% BY WEIGHT OF AN ADDITIVE CONSTITUTED BY AT LEAST ONE WATER INSOLUBLE SOAP SELECTED FROM THE GROUP CONSISTING OF WATER INSOLUBLE CALCIUM, MAGNESIUM AND AMINE SALTS OF SATURATED AND UNATURATED FATTY ACIDS, SAID ADDITIVE COMPRISING AT LEAST 50% BY WEIGHT OF UNSATURATED FATTY ACID SALT, AND GELATINIZING THE MIXTURE THUS OBTAINED. 